Mycoplasma gallisepticum is a pathogen of the avian respiratory tract. Sporadic outbreaks, having important economic consequences, occur in turkeys and broiler chickens, and remain a costly enzootic infection in commercial egg layers. The cytadhesin protein of the organism is a virulence determinant involved in the attachment of the organism to host surfaces during infection via recognition of host receptors.
In current practice, prophylactic immunization of fowl against M. gallisepticum related disease involves either controlled exposure to attenuated vaccine strains (for example the "F strain"), or the use of inactivated, whole cell oil emulsion vaccines. Each of these approaches has certain disadvantages. For example, live vaccines can produce disease or impair reproductive function. Inactivated vaccines, while generally effective in preventing disease in immunized birds, do not reliably prevent infection, and may allow spread of infection and disease to unvaccinated birds.
Improvements are also needed in current diagnostic tests for the presence of M. gallisepticum in fowl. Current methods for diagnosis of M. gallisepticum infections by serological methods typically employs whole organisms to assay the presence of antibodies against M. gallisepticum. These tests are costly and time consuming, and can produce false positive or false negative results due to nonspecific reactions.
U.S. Pat. No. 5,026,636, issued Jun. 25, 1991, discloses the isolation of the P1 cyadhesion gene from M. pneumoniae. U.S. Pat. No. 5,158,870, issued Oct. 27, 1992, discloses diagnosis of M. genitalium infection using monoclonal antibodies.